Currently, during the production of the wet process equipment in the panel production, it is necessary to use a chemical tank to supply chemical liquid having an accurate temperature to the wet process equipment. The temperature control of the chemical liquid is completed in the chemical tank. The conventional chemical tank comprises four devices: a process cooling water system for a cooling effect, a heating rod for heating, a circulating pump for distributing the chemical liquid evenly and a temperature detecting sensor for making feedback a current temperature of the chemical liquid. These four devices are configured for controlling a specific temperature of the chemical liquid by PID control.
The methods of conventional technology have the following drawbacks. First, when the heating rods are operated, a partial temperature usually reaches 200 or more, the chemical liquid can only be uneven heat exchanged on a surface of the heating rod. Second, the partial temperature of the heating rods is excessively high so that the organically chemical liquid has a risk of fire. Third, PID is configured for controlling the working of the process cooling water system and the heating rods to complete the temperature control through the feedback of the temperature detecting sensor, which results in waste of energy. Fourth, the heating rods belong to a partial heating manner and the heating power is not adjustable during heating. Fifth, the life time of the heating rods is short. The above-mentioned drawbacks of the conventional technology need to be solved.